Envision Matrix and other things

I found a nice post on the forum from Patricia that could come in very handy for programmers.
Source: http://forums.datatel.com/viewtopic.php?f=28&t=12512


In the first question about adding the comments field to an existing LIST.VAR... You were only seeing the first line, because a list inside a list doesn't work. Further down in the thread, you saw where the CONVERT @VM TO \" \" IN ... converted the list for this line into a paragraph (sort of) by replacing the character that made it a list (@VM) with a space. Then, by putting the \"paragaph\" into the window's list variable, you would have been able to see all of it on a single row of the window (albeit, maybe limited by the size of the field, so maybe not see it all )

DIM = this is a straight UniBasic command to dimension a matrix in memory. In other languages, this may also be referred to as dimensioned arrays. Referenced in Envision and UniBasic with parenthesis, most other languages with square brackets. Since Envision is an extension of UniBasic, most of the UniBasic commands can be used in Envision. Matrices can be one dimensional or two dimensional. Think of a matrix similar to a spreadsheet.


Code:
DIM XM.TEMP(15) is a single row with 15 columns
DIM XM.TEMP.TWO(15,5) would be an entire page, 15 columns by 5 rows

MAT is the companion to DIM. Where DIM sets aside the size of the matrix, MAT is the command used to initialize the dimensioned array. You usually see it initializing a matrixto null

Code:
MAT XM.TEMP = \"\"
MAT XM.TEMP.TWO = \"\"
Matrices/dimensioned arrays can be very powerful and can be equally complex.

EQUATE is a command used by the compiler. It literally takes what you type and replaces it with the equated value in the object code. Usually equates are used for programmer readability. You see every table in Datatel has an assoicated \"equate table\" in the app.INSERTS (or maybe it's the app.SOURCE). For example


Code:
EQUATE LAST TO 1
EQUATE FIRST TO 3
Then when a record is read from the PERSON file, the individual fields are parsed into their v-dots using the equates.


Code:
V.LAST.NAME = R.PERSON<LAST>
V.FIRST.NAME = R.PERSON<FIRST>

is the same as saying V.LAST.NAME = R.PERSON<3>
An advantage of this approach is that something moves around to another loccation, you only need to change the equate statement and then recompile the code rather than change every place where you typed the literal location <3>.

PRINT versus X.LINE - PRINT is the UniBasic command to send stuff to the output device defined with the SETPTR command (like the printer or _HOLD_ file). PRINT_DETAIL is an Envision thing.

X.LINE is usefull for programmers to build their own line of data to be sent to the printer/output device rather than fighting with Envision's report writer... it's just easier some times

CRT is a UniBasic command to send stuff to the console/screen and is now banned in Envision.

SHOWA is the new GRSS debugger built into Envision by Datatel and would be the new replacement for any CRT statements you are using for debugging. It's really very cool. Look at the GRSS, GRS1 and GRS0 mnemonics and see if they have on-line help. It's the replacement for doing something like

Code:
IF DATATEL.DEBUG THEN
XL.DEBUG.MSG<1> = \"v.last.name =\":V.LAST.NAME
XL.DEBUG.MSG<1> = \"v.first.name =\":V.FIRST.NAME
CRT XL.DEBUG.MSG
END

would be replaced with the single line
SHOWA V.LAST.NAME; V.FIRST.NAME

Of course, to use SHOWA, you must use the Envision generator. If you are hacking generated source code (app.SOURCE), you would still use the UniBasic CRT command to get it to display to the console.

CALL versus CALL_SUBR - this is an Envision thing and has to do with the MIO buffers. CALL_SUBR is used by screens and enables DETAIL screens to cancel the commits to the database if it's parent is cancelled. CALL can be used in screens, but will write the data whether or not the calling screen is cancelled or not. CALL is also used in subroutines.